Fix PR10277.

Remat during spilling triggers dead code elimination. If a phi-def
becomes unused, that may also cause live ranges to split into separate
connected components.

This type of splitting is different from normal live range splitting. In
particular, there may not be a common original interval.

When the split range is its own original, make sure that the new
siblings are also their own originals. The range being split cannot be
used as an original since it doesn't cover the new siblings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134413 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 108 insertions, 0 deletions

diff --git a/lib/CodeGen/InlineSpiller.cpp b/lib/CodeGen/InlineSpiller.cpp
index 0273891d69..4bd35c3812 100644
--- a/lib/CodeGen/InlineSpiller.cpp
+++ b/lib/CodeGen/InlineSpiller.cpp
@@ -425,6 +425,7 @@ void InlineSpiller::analyzeSiblingValues() {
       // Check possible sibling copies.
       if (VNI->isPHIDef() || VNI->getCopy()) {
         VNInfo *OrigVNI = OrigLI.getVNInfoAt(VNI->def);
+        assert(OrigVNI && "Def outside original live range");
         if (OrigVNI->def != VNI->def)
           DefMI = traceSiblingValue(Reg, VNI, OrigVNI);
       }
diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp
index 052abad57e..b385fb36bb 100644
--- a/lib/CodeGen/LiveRangeEdit.cpp
+++ b/lib/CodeGen/LiveRangeEdit.cpp
@@ -298,10 +298,16 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
     if (NumComp <= 1)
       continue;
     ++NumFracRanges;
+    bool IsOriginal = VRM.getOriginal(LI->reg) == LI->reg;
     DEBUG(dbgs() << NumComp << " components: " << *LI << '\n');
     SmallVector<LiveInterval*, 8> Dups(1, LI);
     for (unsigned i = 1; i != NumComp; ++i) {
       Dups.push_back(&createFrom(LI->reg, LIS, VRM));
+      // If LI is an original interval that hasn't been split yet, make the new
+      // intervals their own originals instead of referring to LI. The original
+      // interval must contain all the split products, and LI doesn't.
+      if (IsOriginal)
+        VRM.setIsSplitFromReg(Dups.back()->reg, 0);
       if (delegate_)
         delegate_->LRE_DidCloneVirtReg(Dups.back()->reg, LI->reg);
     }
diff --git a/test/CodeGen/X86/crash.ll b/test/CodeGen/X86/crash.ll
index 7c4e64cdf6..b5b1ad45be 100644
--- a/test/CodeGen/X86/crash.ll
+++ b/test/CodeGen/X86/crash.ll
@@ -215,3 +215,104 @@ bb2:
 }
 
 declare i64 @llvm.objectsize.i64(i8*, i1) nounwind readnone
+
+; PR10277
+; This test has dead code elimination caused by remat during spilling.
+; DCE causes a live interval to break into connected components.
+; One of the components is spilled.
+
+%t2 = type { i8 }
+%t9 = type { %t10 }
+%t10 = type { %t11 }
+%t11 = type { %t12 }
+%t12 = type { %t13*, %t13*, %t13* }
+%t13 = type { %t14*, %t15, %t15 }
+%t14 = type opaque
+%t15 = type { i8, i32, i32 }
+%t16 = type { %t17, i8* }
+%t17 = type { %t18 }
+%t18 = type { %t19 }
+%t19 = type { %t20*, %t20*, %t20* }
+%t20 = type { i32, i32 }
+%t21 = type { %t13* }
+
+define void @_ZNK4llvm17MipsFrameLowering12emitPrologueERNS_15MachineFunctionE() ssp align 2 {
+bb:
+  %tmp = load %t9** undef, align 4, !tbaa !0
+  %tmp2 = getelementptr inbounds %t9* %tmp, i32 0, i32 0
+  %tmp3 = getelementptr inbounds %t9* %tmp, i32 0, i32 0, i32 0, i32 0, i32 1
+  br label %bb4
+
+bb4:                                              ; preds = %bb37, %bb
+  %tmp5 = phi i96 [ undef, %bb ], [ %tmp38, %bb37 ]
+  %tmp6 = phi i96 [ undef, %bb ], [ %tmp39, %bb37 ]
+  br i1 undef, label %bb34, label %bb7
+
+bb7:                                              ; preds = %bb4
+  %tmp8 = load i32* undef, align 4
+  %tmp9 = and i96 %tmp6, 4294967040
+  %tmp10 = zext i32 %tmp8 to i96
+  %tmp11 = shl nuw nsw i96 %tmp10, 32
+  %tmp12 = or i96 %tmp9, %tmp11
+  %tmp13 = or i96 %tmp12, 1
+  %tmp14 = load i32* undef, align 4
+  %tmp15 = and i96 %tmp5, 4294967040
+  %tmp16 = zext i32 %tmp14 to i96
+  %tmp17 = shl nuw nsw i96 %tmp16, 32
+  %tmp18 = or i96 %tmp15, %tmp17
+  %tmp19 = or i96 %tmp18, 1
+  %tmp20 = load i8* undef, align 1
+  %tmp21 = and i8 %tmp20, 1
+  %tmp22 = icmp ne i8 %tmp21, 0
+  %tmp23 = select i1 %tmp22, i96 %tmp19, i96 %tmp13
+  %tmp24 = select i1 %tmp22, i96 %tmp13, i96 %tmp19
+  store i96 %tmp24, i96* undef, align 4
+  %tmp25 = load %t13** %tmp3, align 4
+  %tmp26 = icmp eq %t13* %tmp25, undef
+  br i1 %tmp26, label %bb28, label %bb27
+
+bb27:                                             ; preds = %bb7
+  br label %bb29
+
+bb28:                                             ; preds = %bb7
+  call void @_ZNSt6vectorIN4llvm11MachineMoveESaIS1_EE13_M_insert_auxEN9__gnu_cxx17__normal_iteratorIPS1_S3_EERKS1_(%t10* %tmp2, %t21* byval align 4 undef, %t13* undef)
+  br label %bb29
+
+bb29:                                             ; preds = %bb28, %bb27
+  store i96 %tmp23, i96* undef, align 4
+  %tmp30 = load %t13** %tmp3, align 4
+  br i1 false, label %bb33, label %bb31
+
+bb31:                                             ; preds = %bb29
+  %tmp32 = getelementptr inbounds %t13* %tmp30, i32 1
+  store %t13* %tmp32, %t13** %tmp3, align 4
+  br label %bb37
+
+bb33:                                             ; preds = %bb29
+  unreachable
+
+bb34:                                             ; preds = %bb4
+  br i1 undef, label %bb36, label %bb35
+
+bb35:                                             ; preds = %bb34
+  store %t13* null, %t13** %tmp3, align 4
+  br label %bb37
+
+bb36:                                             ; preds = %bb34
+  call void @_ZNSt6vectorIN4llvm11MachineMoveESaIS1_EE13_M_insert_auxEN9__gnu_cxx17__normal_iteratorIPS1_S3_EERKS1_(%t10* %tmp2, %t21* byval align 4 undef, %t13* undef)
+  br label %bb37
+
+bb37:                                             ; preds = %bb36, %bb35, %bb31
+  %tmp38 = phi i96 [ %tmp23, %bb31 ], [ %tmp5, %bb35 ], [ %tmp5, %bb36 ]
+  %tmp39 = phi i96 [ %tmp24, %bb31 ], [ %tmp6, %bb35 ], [ %tmp6, %bb36 ]
+  %tmp40 = add i32 undef, 1
+  br label %bb4
+}
+
+declare %t14* @_ZN4llvm9MCContext16CreateTempSymbolEv(%t2*)
+
+declare void @_ZNSt6vectorIN4llvm11MachineMoveESaIS1_EE13_M_insert_auxEN9__gnu_cxx17__normal_iteratorIPS1_S3_EERKS1_(%t10*, %t21* byval align 4, %t13*)
+
+declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind
+
+declare void @llvm.lifetime.end(i64, i8* nocapture) nounwind